Hello there, first time poster here with a little bit of an issue.
Been riding bikes for over a year now, started on a 1982 Suzuki GS 650 GL. Didn't quite fit me right, gearing was awful for the highway, and the fuel efficiency left a little to be desired for me. Got a 1996 GS500 locally a few months ago and tore it down for painting. Now that it's done and back together I've been riding it around a lot and although I love it as a commuter bike I'm not happy about it's performance when I'm on the expressway.
Here's the issue:
When I am on the expressway in 6th gear around 75-80mph, I can't get the engine to turn over 7000rpm or so. If I try to open the throttle up more, the bike bogs on me and I lose speed. It seems to do fine at lower speeds, and I can get the engine to rev up to red-line through 1st and 2nd, but over 60mph or so it won't rev as high and if I open the throttle all the way the RPM seems to hover right around 5-6k and it coughs a lot. Half throttle I can get the bike to free-rev the whole tachometer.
The previous owner installed a K&N air-filter, and I assumed he didn't re-jet the carbs or re-tune the mix screws and thus was running very lean. I figured too much throttle = too much air and not enough fuel so it's losing power. So, I went to the dealer and bought some 130s and when I took the bike apart and opened the carbs up I discovered that there were already 135 mains installed!
So I sprayed some carb cleaner into the lower half of the carbs, closed 'em up, put 'em back in, then thought about the mix screws. So I did the standard procedure:
Warm bike up, close mix screws, open 1 turn, set idle at 1000rpm, open screws until RPMs don't climb anymore, open an extra half turn, reset idle at ~1200rpm.
Hopped on the bike, felt good around town, merged onto the expressway, topped out at 75-80 in 6th at around 7k.
So it asks the question, what is wrong with the bike?
Is it possible the mix is too rich and I should go down in jet size? (seems counter-intuitive to me but I won't rule it out)
Is it still too lean and should I move up to 140+ mains?
Is my fuel delivery system starving the carbs? (I should mention, the factory petcock is bypassed. I'm running from the tank's reserve nipple to an in-line on/off through a filter and into the carbs)
Is the little 487cc engine just not powerful enough to haul my overweight butt faster than 80mph? (I haven't weighed myself in quite some time but I'd wager a good guess I'm around 235lbs when I should be 180lbs. 50hp should be sufficient, though. My 650's 70hp could take me up to 85 no problem...)
I don't have the proper spark-plug wrench or a big enough deep-well socket so I can't pull the plugs to see what they tell me. I don't get any backfires, pops, gas smell, or any other signs of a engine running with a poor mix.
Valves did look a little white when I painted the headers, which led me to think running lean to begin with, but with 135 mains I'm not sure what to think anymore...
Thanks for any suggestions.
Pics for fun!
(http://imageshack.us/a/img18/1290/gs500newpaint3.jpg)
(http://imageshack.us/a/img33/7774/gs500newpaint2.jpg)
(http://imageshack.us/a/img51/7690/gs500newpaint1.jpg)
Well, you have mentioned all the things I would be looking for. Air filter and carbs basically. It's odd that it is only above 60 that there is a problem. What I can say is the bike definately should be able to hit 100+ no problem, so yes the little GS should be able to haul your ass up to that. :)
-Anthony
First...that is a VERY nice red...loving that color.
Sounds like you know your way around the bike, so that's good. Also seems like you know what you are doing as far as troubleshooting and adjustments. The bike should certainly get you past 80, but 6th is going to be a bit sluggish in general. Can you rev it up through 5th to say...9-10K? Get it up that high before you hit 6th? By 80, on a naked bike, you are asking a lot of a 500cc motor as far as overcoming wind and still accelerate strong. Either way, yes, you should be able to go faster...just not much, and not quickly...90-100 naked and your weight is probably all it's got. I'm about the same size so I feel your pain.
It's important to be able to at least look at the plugs.
Perhaps their worn....perhaps their gapped wrong....perhaps the mixture is out................perhaps u want to change them to make sure(maybe to Iridium)
Thanks for all the quick replies!
Thanks for the compliment on the paint, Soloratov. It's actually a very dark burnt orange, and it's extremely tricky to photograph. It's all House of Kolor paint, Tangerine over Galaxy Grey (and it was EXPENSIVE :o).
In direct sun it looks like a bright yellow-orange, indirect sun it looks burnt-orange, in shadow or at night it looks maroon/burgundy, and under fluorescent light it looks red... I could take a million photographs of it in a thousand different locations in morning-noon-evening-night-indoor light conditions and it'll NEVER look the same or nearly as good as in person! The pics I posted were taken during overcast weather.
Well worth the price, that House of Kolor paint, as long as you have the skills to air-brush it.
This is more representative of the true color, I think this may have been taken before the clear-coat:
(http://imageshack.us/a/img585/7221/gastankinthesun1.jpg)
Anyway...
I don't really recall the max RPM in 5th or even 4th. I'm usually a pretty modest rider, not really flooring it everywhere. I typically ride the engine no higher than 7-8k around town before I upshift, so I'm usually in 6th by the time I hit the end of the access ramp to the expressway and at appropriate hwy speeds (60ish).
I'll give it a test ASAP and post the results here. Looks like rain any minute now and the next few days aren't looking dry so it might take me a few days.
I'll agree that the plugs are pretty transparent when it comes to determining engine issues, I'll try to get ahold of the right socket ASAP. I only have a Std size plug socket at the moment and my biggest deep-well metric socket is a 15mm and it looks like I need a 17 or an 18...
They are NGK plugs, not sure if they're iridium or not. Either way, what is the gap spec on them? I'll check it as soon as I can get them out.
It should be able to go past 80 w/out bogging. But why so fast? Are you in a hurry? Still, I would also be annoyed knowing my bike bogs when it shouldn't.
I'm 240lbs, probably 250 with gear, with a naked GS500 and I can cruise comfortably at 140kmh. Albeit, I'm getting pummeled by wind, but I can roll on the throttle and easily bump it up to 150 or 160 in 6th in a hurry. No bogging, no feeling like power is running out (although I'm sure above that it will be). Haven't found top speed yet, but the little twin has surprised me so far. This is with jets (whatever the standard suggested upsize is, I forget), K&N drop in, and full Jardine exhaust.
High speed bogging is usually a perfect example of wrong AFR's. The engine isn't under enough load at lower speed for the bad mix to show.
I'd check the plugs quick before you melt something.
Quote from: Erika on June 15, 2013, 09:21:31 PM
It should be able to go past 80 w/out bogging. But why so fast? Are you in a hurry?
Clearly you haven't driven in Chicago :laugh:
On surface streets everyone does at
least 5mph over the speed limit (usually 10 over will get you by comfortably), and the local interstates are like America's Autobahn. If it says 55mph you do 65 in the slow lane... As you get closer to the "passing" lane you speed it up to at least 75, and even then many people will be trying to go around you.
Problem is, everyone drives like an ass. The fast lane is "go fast or GTFO" since people like to ride your ass (especially since people don't know how to use the left lane properly and will "cruise" in it and not move over for faster vehicles), and the "slow" lanes seem to be populated by semi's and idiots so on a bike you have to be in the left two lanes just to be safe. The price of being there is to go fast.
Hell, just today I hesitated on passing an early 90s Chevy Blazer with bad shocks and a bad steering dampener that was "walking" in it's lane. I thought the driver would loose control and cross lanes, roll it, or spin out any second! He was in the middle-left and I was in the left; eventually he wised up, got over, and slowed way down to calm his truck down...
A few days ago I got caught in some heavy rain heading home from work. I was going 55 in the 55, in the far right lane, and I look in my mirror and a driver is only about a car's length away from my back side. I gesture to back up a bit, and they get the hint for about 5 miles and do it again. I repeat with a gesture to kindly f**k off, and they went around.
I can't even tell you the last time I saw a state-trooper on the road. Certainly they don't patrol the interstate every day, and often times I'll drive for weeks without seeing one. Problem is, with such a reduced enforcement presence and with so many drivers with such a blatant disregard for speed control ordinances, you can't really do anything about it anymore.
People see a car pulled over on the expressway and they push the pedal down even more. Why? He's busy, and there isn't another cop for miles...
If everyone is doing 20 over, how do you pull someone over for speeding? Hell, you'd be pulled over for going the speed-limit on the grounds of "impeding traffic".
Until the staties start doing mass ticketing with the whole force covering a 10 mile stretch, driving all offenders into an oasis where more officers are waiting just writing tickets, it will remain America's Autobahn and I'll be going with the flow...
So, that being the case, having room to move faster will keep me out of physical trouble. Not that I'd hold the bike at 100mph, but being able to speed up 10-20mph to pass someone, change a lane, or avoid being merged into would be very welcome.
... Sorry about the tangent :laugh:
Sounds a lot like Ontario...
I try to avoid highways here like the plague, but sometimes we just have no other options unless you want to add on 30min to your 2 hr drive. We have people going 100kmh in the left lane thinking they have every right to do so and then we get traffic jams in the right two lanes from people trying to pass and, truckers and other vehicles going 100. If you go on the REAL autobahn in Germany it's like heaven. It's unbelievable how the flow of traffic there can be so smooth with 4 lanes while we get bottle neck traffic jams with 8 lanes. Just shows how far highway etiquette can get you.
Quote from: Wagoneer on June 16, 2013, 02:05:55 AM
Just shows how far highway etiquette can get you.
So true...
Quote from: Watcher on June 15, 2013, 07:43:23 PM
Pics for fun!
(http://imageshack.us/a/img18/1290/gs500newpaint3.jpg)
(http://imageshack.us/a/img33/7774/gs500newpaint2.jpg)
(http://imageshack.us/a/img51/7690/gs500newpaint1.jpg)
I REALLY like the colour of your bike :bowdown:
Are you talking about 80 mph indicated or an actual 80 mph, speedo error on GS is 8-10%? When you bog down at 75-80 mph have you tried dropping to 5th to see if it will go faster? Redline on stock geared GS is over 100 mph in 4th if it will pull it, power drops off fast after 8500 rpm on a stock GS. Do you have stock 16/39T gearing, might have been modified by PO. Were you on level ground when bogging down?
I had my 97 GS up to 110 mph indicated once about 11 years ago with 240# me onboard, GS had a big Plexi 2 windshield on it, was in mountains of upstate NY. Probably about a honest 100 mph. Made about 4 trips between NE OH and Smoky Mtns back then travelling 70-80 mph indicated and on I-77 south thru WV there was one uphill the GS would just barely hold 80 but would move out easily with a downshift to 5th.
My 97 and 02 GSs have both been stock for the 175k miles I've used them, no carb mods at all. Here's a list of data from all published road tests of the GSs I've seen: http://www.gs500.net/gallery/data/500/GS500tests.jpg
Quote from: Watcher on June 16, 2013, 01:35:11 AM
Clearly you haven't driven in Chicago :laugh:
I guess not. In New York the cops are nazis and really enforce everything, especially towards motorcycles. They hate anything on two wheels for some reason. In fact, we just got pulled over yesterday because our friend had an antique Vincent with old-timey plates. We all asked him, "What? Were we speeding?" Another saying we use when someone is pushing around in a crowd is "What? Are you in a hurry?" :)
Anyway, that's a groovy color... nice paint job. One thing that has made my bike bog before was a breather tube... the end of it was facing forward and catching a lot of wind back up into the system. I made it face the other way and the symptom went away. Not sure if that 's the case for you, but might be worth looking into.
Sounds like AFR to me. I would want to rule out compression as well, could be a leaky valve or bad rings. Past that, you really need to take a look at the plugs and see where you are with the mixture.
Before you make any more changes to the jetting, I would verify the type of jet needles you have to determine if it's stock or not. Stock will only have one position for the e-clip, and have 5DH8 stamped on them along with the mikuni symbol. Also verify that the 135 jets are genuine mikuni; otherwise they could have a different sizing scheme. Mikuni jets have this symbol stamped on them:
(http://i265.photobucket.com/albums/ii224/dtilford/GS500/mikuni.jpg)
Lastly with the carbs, verify fuel level in the bowls with a clear tube from the drain and the petcock on prime. The level in the clear tube should reach the level of the float bowl gasket plus or minus 1 mm. If it's not, then you need to adjust the float height. Lastly, check for air leaks (spray starting fluid around the seals on all sides of the carbs and see if the rpms change), and make sure the filter is clean.
What kind of exhaust is that?
Quote from: Erika on June 16, 2013, 07:39:15 AM
Quote from: Watcher on June 16, 2013, 01:35:11 AM
Clearly you haven't driven in Chicago :laugh:
I guess not. In New York the cops are nazis and really enforce everything, especially towards motorcycles. They hate anything on two wheels for some reason.
Really? Where are you riding? I have done some really dumb things...including speeding...20+ over...and never had one even look at me. Granted it wasn't intentionally malicious by any means, just one of those, crap I got caught feelings. I can actually say I don't think anyone I know has ever been stopped by a cop on a bike. That seems odd.
I agree with Erika, it sounds like your carb breather tube may be routed into the wind. It gives the exact same symptoms your describing.
Quote from: Watcher on June 15, 2013, 07:43:23 PM
(http://imageshack.us/a/img18/1290/gs500newpaint3.jpg)
Good to know someone else uses the helmet hook to carry things! That's how I bring my lunch to work.
i think you might be lean on your needle.The needle,s in your carbs should have notches in them lift up 2 grooves then try it out .if your needles are to low your main jet will never pass enough fuel even if you went to a 150 main jet.let us know if it improves.
You know, now that you guys are mentioning it the overflow tube for my carbs is missing. I have a barb that goes to nothing...
There is a PepBoys right down the road from my work, I'll stop by there on the way back and hook it up if I can.
Speaking if which, weather forecast cleared up so I took the bike out today. I may have spoke too soon earlier, the highest I can get in any gear is 8k and no matter what gear I'm in I seem to top out at 80.
My boss pulled my plugs, they're iridium and he says they look normal with a slight tendency towards lean. I trust his opinion, he's been building and racing motorsports longer than I've been alive.
He suggests going up to 140s, I'll be sure to check the breather and needles before hand, though.
I'll also do the outside carb spray test as well.
No tube or non-rear facing is a tiny detail, but I can assure you it matters. When I put my bike back together this spring I left the tube off just to test ride...and it ran like crap! It's weird, but that small amount of pressure must make a lot of difference.
Watcher, make sure you spray both side (in and out boots) and around the throttle shaft.
Yes get a tube on there and route it out of the wind like next to the battery. I have a '93 with 140s in the main and two washers on the needle. I get a slight bog between 6-7k but above that she will rev up to 10k if I wanted to, for the freeway I accelerate from 7k and up, anything below that is too boggy. I tip the scales at 260 and have no problem gettin up to 90-100mph on the speedo. When I did a carb sync it made a big difference on my bike too..
Is there any kind of breather apperatus at the end of the overflow line? Or is it just an open ended tube?
I also appear to be missing the drain line e on my air box, would that change anything?
Just open for the carb vents, drain for air box actually has a water release valve on it though, I would think not having that would not affect your speeds or performance but would allow dust and stuff to bypass the filter..
Haven't had a chance to run the breather hose yet, I just got home from work. Needed a drink, needed to get tools, and wanted to post this before I forgot.
I can't run the bike full-throttle at all. I never really gave the grip a good twist before...
Half-throttle it'll free-rev up to red-line. If I go full throttle it bogs, sputters, and won't climb any higher than, like 6k.
Then if I just let go the engine stalls.
On the freeway I top out at 75-80, no matter what gear I happen to be in, but seeing as I have the full throttle issue I have to be in 5th/6th to really even get that fast.
I'll update later today if/when I do some tinkering.
Chicago? Edens expressway minimum is 90MPH. Ask me how I know this. Been up there twice on the GS. WOT, still getting passed. I was on my way to Antioch, IL on WI border.
I say look at plugs, carb, kinked fuel line, and jets. I had a similar problem on an old gs450 and it was ignition related, but start with fuel.
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Quote from: Soloratov on June 16, 2013, 11:34:18 AM
Really? Where are you riding? I have done some really dumb things...including speeding...20+ over...and never had one even look at me. Granted it wasn't intentionally malicious by any means, just one of those, crap I got caught feelings. I can actually say I don't think anyone I know has ever been stopped by a cop on a bike. That seems odd.
New York City. Cops here hate anything on 2 wheels... not kidding...
http://www.telegraph.co.uk/news/newsvideo/7891735/Policeman-pushing-man-off-bike-watched-by-millions-on-YouTube.html
Cops in the city also set up road blocks by bridges and pull over only motorcycles. If anything is amiss, they load your bike up on a truck and impound it at your expense. Of course, if you're all legal, nothing will happen. But why only motorcycles when there are so many illegal drivers also kicking around in the city?
We were riding to New York City back from Rhinebeck from an antique motorcycle show and were on the Taconic. A highway patrolman pulled 4 of us over... we were joking when we asked if we were speeding. (Antique bike riding with us, although he could cruise on that bike if he wanted to). The problem was the antique license plate. Luckily the owner of the bike was very charming and just talked about the history of the bike, so the cop let us go. Thank goodness there weren't any bridge blockades that day.
Updates!
Replaced:
Fuel lines
Fuel filter
Breather hose (routed up and over the air-box, down the battery tray, and out near the swing-arm)
Vacuum plug on the carbs
Flasher (needed one of these while I was at it)
Checked:
Carb needles (stock, no mods)
Carb diaphragms (perfect)
Cleaned:
Carb needles
Jets
Carb uppers
Choke pathway
Adjusted:
mix screws (reset via proper procedure)
idle (set at ~1200)
Added:
Full tank of 93 octane
Verdict?
Well, I can full-throttle it and the bike doesn't complain, sputter, pop, hover at 6k, then die as soon as I let off. It still doesn't red-line at full throttle, but it gets pretty darn close.
After flicking the throttle the RPMs take their time settling back to idle speed. That means it's still a touch lean, right?
Around town rideability is better, more instantaneous power, less "all bark and no bite", I can grab and handful and it takes off instead of bogging, high-gear pulls are actually affecting speed rather than just making noise.
I have not gone expressway yet. I'm tired and it's kind of cold out.
I also have not sprayed around the carbs while the bike is idling to check for intake/vacuum leaks, I used up all my carb spray...
Overall, given the relaxed falling RPM and the not perfect full-throttle, the bike is operating much much better.
As long as I take the bike to work tomorrow, I'll have a high-speed update.\
Thanks for all the help so far, guys.
Cold out? It's summer. You have not lived until you ride in 18* F. :).
Glad it's running better.
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Quote from: jestercinti on June 18, 2013, 10:10:42 PM
Cold out? It's summer. You have not lived until you ride in 18* F. :).
Cold for summer :icon_rolleyes:
In the 50s, overcast, and foggy (wet) all day. Just kind of sucks to be out because it's just damp enough that the wind makes it feel way colder than it actually is and since there's no sun you don't warm up by stopping... Other than the engine-block...
If it counts for anything, when I bought the bike it was a couple of counties over. I rode it for a little over an hour and a half straight, mostly expressway (75+ miles), in 31°F weather.
Had sock liners, socks, boots, long underwear, flannel lined jeans, underarmour, Columbia fleece top, riding jacket, latex gloves, polypropylene glove liners, riding gloves, balaclava, scarf, shemagh, and helmet on. Wasn't too bad. Initial cold-shock sucked until I stopped getting colder, then I just cozied up to the gas tank, squeezed my shins in as close to the block as I could, and made fists and directed the bike with my palms.
Stopped once 20 minutes in to pee, did the rest in one whole bite.
I've ridden my last bike ('82 Suzuki GS650GL) in similar conditions for not nearly as long, but with improper attire. I had to stop at a gas station once after about a half hour because I was scared of frost-bite on my hands. I even had liners and leather riding gloves, but the wind was really cutting through the seams and cloth parts of the gloves. Did a bare-hand hi-five to the header a few times, played patty-cake with the block, then grabbed hold of the crank-case cover with both hands giving the whole bike a big bear hug. Held it until it hurt. Put the liners back on. Bear hug. Gloves back on. Bear hug. Actually damaged the leather and shrunk a finger on one of the gloves doing that.
Got me home with all my digits intact... This is when I thought of using latex exam gloves to beat the wind. Works wonders, try it next time you go out in cold weather!
Would I do it again? Yeah, as long as the ends justified the means like getting a sweet deal on a GS500 :cheers:
Would I do it to commute? My truck would be my first choice, but if I knew I was going to I'd get a 1-piece snow suit and those cold-weather gauntlets for the bar ends so I could slip my hands inside them to work the controls...
I'm glad it's running better, too. I've got my fingers crossed that the bike will be better on the interstate. If not we'd be back to the drawing board >:(
Expressway update!
Top speed increased from ~75 in calm weather to ~85 with a strong head-wind.
Throttle manipulation went from "sweet-spot the middle" to "twist to go faster".
I can run the throttle at about 95% as opposed to 50%, now, bike seems like it gets in the 9-10k rpm range no problem now, and I should be able to hit 100 with no wind.
6th gear pull from 70mph to max was all twist. Didn't complain or bog, just started accelerating.
Looks like I can keep up in the fast lane now.
Still a little buggy, might still benefit from going even bigger on the mains (140s?), but it runs great right now!
Just read the entire thread: you said it has a K&N filter, but which one? There are actually 3 different types if I'm not mistaken. And you said the needles were stock? There were no extra shims (washers) under the clip to richen out the midrange?
Quote from: Big Rich on June 21, 2013, 06:19:09 PM
Just read the entire thread: you said it has a K&N filter, but which one? There are actually 3 different types if I'm not mistaken. And you said the needles were stock? There were no extra shims (washers) under the clip to richen out the midrange?
K&N, conical, inside the air-box. I didn't install it so I can't give you any more information than that...
No, needles were stock. Midrange is fine, though, it's the top-end that is bad.
Anyway, I have another update.
Went to the dealer and bought 140, 145, and 150 mains to play around with.
Put the muffler in the band-saw at work, cut the cap off, pulled the baffle out, welded the cap back on. Sounds great! A little on the loud side but not too bad. It'll hold me over until I get a V&H.
And because I wanted to see what it would get me, I put the 150s in the carbs. Pretty sure it's running too fat now. I got a lot more low end power, midrange is about the same, but the top end is spotty now. Not like before where it would bog down, but it kinda just breaks up at 8-9k and it pops a little if I let it jake-brake down a bit.
I'll try the 140s next.
Watcher, go back to page 1 and read Twinrat's post about the washers. That's why I asked specifically about them.
I'll check again but I didn't think the needles had grooves in them to change where the clip goes.
I'll post updates when I find out.
Edit: my needles only have one position where the clip can go, I don't have any secondary grooves.
You'll need small washers - I think #4 washers? You can buy a package of misc washers from Radio Shack for a couple bucks. They go in between the clip and that thicker plastic ring, raising the needle's height.
i think Big Rich is right about the washer size it should have a hole diameter of .125" or 3.2mm .There should be a washer on top of the needle clip that acts as a seat for the spring in the 05 to 09 models take this as a trial and put it below the needle clip this will lift it to richen your mixture .it should be about .040" or about 1 mm thick .Do not bother with the .020"or1/2mm sizes as there is no discernable difference .needles with grooves have there grooves 1mm apart.the washers are stainless steel .
I'll give it a shot.
I spent all day today running different size jets and playing around with mixture screws. I tried 140s, 145s, and 150s, and ended up putting the 135s that were in originally back in. Seems like it runs the best with those.
It's weird though, I had my boss help me try to diagnose the problem and he says that it breaking up with full throttle is usually a sign that it's running too rich. However, I have the white plugs and exhaust valves to prove that it's running lean.
So we checked everything we could check with basic tools and came to the conclusion that the mixture still isn't right. And if we can keep going fatter on the mains and it always breaks up top side, yet still runs evidently lean, either it's a problem with the low jets or the needles (diaphragms/sliders not working right?).
It just seems weird to me that shimming the needle would solve the problem. I mean, it's made to lift up when it's pulled up via the diaphragm by vacuum from the engine. So, the faster the engine turns, the more air it sucks, the more vacuum it makes, the higher it lifts the needles, the more gas it lets in. Simple.
Lifting the needles via shims to make up for it not lifting high enough by vacuum seems like compensating for and ignoring a bigger problem. Like putting a poster over a big crack in the drywall. It might look better (run better) but there's still a big crack in the wall (slider issue?).
Unless the needles were set too deep from the factory in an effort to lean the bike out. But I'd think needles are needles and they work how they work, fuel issues would be jet related.
But, this is the first time I'm going this deep into carb related problems and plenty of people know more than me. If you all say shim the needles, then they shall be shimmed :cheers:
I'll post updates with what I find.
If that doesn't help I'm going to the dealer and buying bigger low jets.
You're on the right track thinking about engine vacuum lifting the needles. The part that changes with shims is this:
The slides are what move when the engine creates vacuum (we can skip over a lot of details here), and the needles have a set height in the slides. At the bottom of the "fuel column" is the main jet, it is screwed into the emulsion tube, and the needle never actually comes out of the emulsion tube. By shimming the needles, you are allowing more gas into the motor essentially at all times. While shimming the needles affects your midrange mixture, at high rpm WOT they do affect how much gas is being sucked up thru the main jets.
If you look around for it, there is a graph somewhere online that shows the affect of each part of the fuel system (pilot jet, main jet, needle jet, etc.). There isn't any kind of "shut off point" for any one part: they all overlap. I'll see if I can find that, actually......
http://www.dotheton.com/forum/index.php?topic=16745.0
Found it! You don't have to read all of it if you don't want to. Some of it even isn't 100% true / relevant.
Okay, first off, im a fan of your paint job.
now for a serious answer, ive heard its a common problem when you have after market filter setups (pods or lunchbox etc.) that the wind at higher speeds will create a kind of "bubble" around there making the airflow drop significantly with the vacuum created if i remember right, the over-flow gets back-pressure as well. If anything else comes to mind (probably after waking up) i'll update this
Well, I'm still running the stock air-box. I just have the filter portion changed out.
And it really sort of happens at all speeds, not just highway speeds. If I really get on it, it just breaks up and can't do anything.
Update:
Shimmed the needles, problem got worse. Where I used to be able to get it to red-line as long as I didn't full throttle, now it just won't get over 8-9k at all.
Talked to some other guys I know, one in particular is very knowledgeable about this kind of stuff, and we're now thinking the culprit could be ignition related.
As we're adding fuel the problem gets worse, and the bike on a whole is still running lean, so it could be that when we add more fuel it's putting out the fire, so to speak.
Could be bad plugs (wrong gap or physically broken), bad wires, bad coils, or bad timing.
Plugs are cheap, I'll toss some new ones in and see what happens.
Had this happened once. Everything said fuel starvation, and I mean everything. Looked at ignition, found out after 2 days it was a CDI Ignition box failing. Replaced, and ran like new.
Start with ignition pickup, coils, wires, and plugs. That's easy. If not, it may be your CDI box. Check all connections too for corrosion.
Quote from: jestercinti on June 24, 2013, 12:52:10 PM
Had this happened once. Everything said fuel starvation, and I mean everything. Looked at ignition, found out after 2 days it was a CDI Ignition box failing. Replaced, and ran like new.
Start with ignition pickup, coils, wires, and plugs. That's easy. If not, it may be your CDI box. Check all connections too for corrosion.
In the process of weeding out electrical now. Plug wires look a little ratty on the ends, might as well change them.
One piece at a time till we figure it out...
IF YOU ARE TUNING AN ENGINE YOU NEED NEW PLUGS OF RIGHT GRADE . NOW THAT YOUR NEEDLE IS LIFTED IS YOUR MAIN JET ABOUT 145 IF ITS LARGER SAY A 150 YOU WILL DEFINITLY BE TO RICH ..WHEN TUNING AN ENGINE YOU NEED ELECTRICS PERFECT ,LEADS PERFECT, BATTERY PERFECT, AND FLOAT NEEDLES THAT DONT STICK .FLOAT LEVELS AT THE RIGHT HEIGHT ,NO AIR LEAKS. INLET AS WELL AS EXHAUST IF ANY OF THESE ARE NOT RIGHT YOU ARE JUST WASTEING YOUR TIME TRYING TO TUNE IT,YOU WILL SEASAW FROM ONE PROBLEM TO ANOTHER .
Well, I've got brand new NGK Iridium plugs in it, my main jet is currently 135, battery is good, I'm checking wires/coils ASAP, float needles are free, floats are set right, fuel flow is good, no vacuum leaks, no intake leaks, no exhaust leaks...
All I can do now is go down the list of electrical starting at the end closest to the motor...
Maybe you are lean at idle, and rich at WOT. That might cause you to see white plugs and valves, but you could still be rich on the top end. With the stock airbox and a K&N drop-in filter, the suggested jetting on the matrix is 127.5 mains. I personally got tired of messing with the different airfilter mixture issues, and I went back to the stock filter with 125 mains and I've been happy since.
Quote from: bombsquad83 on June 25, 2013, 06:09:04 AM
Maybe you are lean at idle, and rich at WOT. That might cause you to see white plugs and valves, but you could still be rich on the top end. With the stock airbox and a K&N drop-in filter, the suggested jetting on the matrix is 127.5 mains.
That's what I'm thinking, I'll have to order some bigger pilot jets. But wouldn't the main jet affect midrange more than the pilot jet?
If I have a free-flowing exhaust, that'll need bigger mains in addition to the filter mods.
Does 135 seem too big for a straight-pipe and the k&n?
here is a good way to tune your carb .Mark your throttle grip with a white mark then twist the throttle gently till you have taken the slack out of the cable now mark the housing oppisoite the mark .wind the throttle round till it is wide open and make another markon the throttle grip oppisite the mark on the housing .Now divide the gap between the two marks into 4 equal gaps .You can now determine which part of the throttle circuit you want to tune ,first 1/4 throttle is for the idle circuit 2nd 1/4 throttle is for the slide circuit third 1/4 throttle is for needle circuit and wide open throttle is for the main jet All these curcuits overlap into each other to give a smooth transistion into the next.